Remote sensing for resources development and environmental management: Remote sensing for resources development and environmental management

Damen, M. C. J.

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Multivolume work

Persistent identifier:: 856342815

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856342815

Language:: English

Additional Notes:: Volume 1-3 erschienen von 1986-1988

Editor:: Damen, M. C. J.

Document type:: Multivolume work

Volume

Persistent identifier:: 856343064

Title:: Remote sensing for resources development and environmental management

Sub title:: proceedings of the 7th international Symposium, Enschede, 25 - 29 August 1986

Scope:: XV, 547 Seiten

Year of publication:: 1986

Place of publication:: Rotterdam; Boston

Publisher of the original:: A. A. Balkema

Identifier (digital):: 856343064

Illustration:: Illustrationen, Diagramme

Signature of the source:: ZS 312(26,7,1)

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Editor:: Damen, M. C. J.

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Volume

Collection:: Earth sciences

Chapter

Title:: 2 Microwave data. Chairman: N. Lannelongue, Liaison: L. Krul

Document type:: Multivolume work

Structure type:: Chapter

Chapter

Title:: Digital elevation modeling with stereo SIR-B image data. R. Simard, F. Plourde & T. Toutin

Document type:: Multivolume work

Structure type:: Chapter

162 rectified using few GCPs and a second order polynomial fit between image and map coordinates. In order to retain the parallax effect in these pseudo-rectified (intermediate level) products, GCP locations must be specified in elevation above an arbitrary datum plane as well as projected position. The correction to intermediate level imagery also requires knowledge of incidence angle 0^ for each GCP. An orbit model derived from the initial ephemeris data for each path was established in order to provide the incidence angle estimates for any point (see Figure 1). Consistency between relative positions as measured from the orbital model and GCP coordinates and those from ground/slant range values obtained from the imagery were also used to refine the positioning of the orbital flight. Those new ephemeris values were subsequently used for the three-dimensional terrain modeling. 2.1 Orbit model The shuttle position in a Cartesian coordinate system can be specified completely either by a set of six orbit elements (p,Q,I,W,e x ,ey) (see Figure 2) or by six vector componpnts - a position vector It plus a velocity vector £. As these parameters evolve with time, variation resulting from non-spherical and non-homogeneous earth make it easier to handle these parameters in their orbit element form. X-Y: the equatorial plane; S: the shuttle position; 0: the center of the earth; p: the Euclidean distance between S and 0; N: the ascending node; P: the perigee of the orbit; I: the inclination of the orbit relative tc ascending node N; Q: right ascension of the ascending node; oj: the argument of the perigee; W: the argument of the shuttle (ui + true anomaly); Figure 2. Geometry of the elliptic orbit movement. Path and position of the shuttle can be extrapolated using linear development of orbit equations, for any time t^=t + At, providing we know at least one set of parameters. Considering that ephemeris data were available approximately every ten seconds, it has been sufficiently accurate to keep only the linear variation part of the orbital parameters. Assuming also that e x and ey (which are the components of eccentricity vector and are expressed as follows: e x =e cosw; ey=e sinw, for a quasi-circular but non-equatorial orbit) are relatively constant over a short period of time, the development of the osculatory parameters as a function of time reduces to the following: p = p 0 + 6p t Q = Qq + 6Q t I = I 0 + 61 t W = W Q + 6W t where linear variations 6p,6I3,6l,6W are known by celestial mechanic laws. Taking the image centre as a reference point, linearization of the osculatory parameters for any time tj**t allows for an accurate position S of the shuttle for each corresponding image point M^. Considering that parameter linearization and shuttle position make it possible to know the time at which any ground point was imaged and that shuttle apparent heading (taking into account for earth rotation effect) is orthogonal to the line of sight, (Figure 3), one can write the line of sight equation developed as a function of time which makes the scalar product of the two following vectors equal to zero: [X( ti ) - t ± t e - XiJ.foti) -7 e ]=0 where • is the scalar product operator; X( ti ) is the shuttle position vector at time Jrl* X(t^) is the shuttle velocity vector at time " e is the earth velocity vector; Hfj. is the geocentric coordinates of point M^. Figure 3. Line of sight representation in non-inertial (terrestrial) reference system. Developing this equation, we obtain this non-linear expression for the time t-^: t = 1 i [arcsin(C) - y - W ] 6W o where C and y are a function of V e , and of the osculatory parameters also a function of t^. If an approximate value of the viewing time t^ 0 (obtained from image measurement) is known for each point M^, one can use an iterative computation process to refine the value of t^ at each step:

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